Hydraulic oil is an industrial lubricant used in many applications, from gear pumps to axial piston pumps to heavy-duty farm and industrial equipment. All hydraulic oils should prevent components from excessive wear and maintenance costs even under extreme temperatures. The deterioration can result from a variety of factors. Rust is one common problem that plagues small parts in engines, transmissions, and hydraulics systems. This problem often arises from the presence of excess water vapor in the system. Oxidation and foam build up is other problems that build up over time and affect the performance of hydraulics systems. For optimal functioning, a hydraulic fluid must be relatively incompressible and must flow readily. In addition, it should provided adequate lubricity for moving parts, stability under anticipated conditions of use, compatibility with materials used to construct the hydraulic system, and the fluids should have the ability to protect system components against chemical reaction with materials which may enter the system. Finally, they should have a minimal impact on the environment.
The hydraulic oil serving as the power transmission medium in a hydraulic system. The most commonly used fluids are petroleum oils, synthetic lubricants, oil-water emulsion, and water-glycol mixtures. The principal requirements of a hydraulic fluid are proper viscosity high viscosity index, anti-wear protection, good oxidation stability, adequate pour point, good de-emulsibility, rust inhibition, resistance to foaming, and compatibility with seal materials. Anti-wear oils are frequently used in compact, high-pressure, and high-capacity pumps that require extra lubrication protection. Certain synthetic lubricants and water-containing fluids are used where fire resistance is needed. Synthetic lubricants also are used in extreme-temperature conditions.
Only slight change in volume during usage, adequate oxidation resistance, for some cases of application adequate de-emulsification capacity, adequate shear stability, if polymer viscosity index improvers are used viscosity-temperature behavior, so that oil changes due to summer and winter operation become redundant, adequately low viscosity-temperature behavior, and minimal characteristics changes of standard elastomers are desirable. Now, pollution and environmental aspects of various products have become important issues. The uncontrolled loss of lubricants can endanger environment by coming into contact directly with the nature (organisms, soil, live water etc.) as a consequence of leakage, throw off, emissions, spillage or careless disposal. Great efforts have been made during the last 25 years by several countries and major industries to develop and find more and more environment friendly—nontoxic products and technologies which have a less negative impact on our precious environment.
In the prior art for producing hydraulic oils, generally, mineral oils or mineral oil with synthetic fluids or complex ester of fatty acids were used. The focus has been on the use of such oil base to enhance the performance.
Reference may be made to U.S. Pat. No. 5,360,565 Junga, Nov. 1, 1994 Petro-Lube, Inc. (Whitemore Lake, Mich.) Hydraulic oil. An improved anti-wear, high-pressure hydraulic oil which contains essentially no zinc or phosphorous is described. The hydraulic oil protects against corrosion and oxidation as well as provides anti-wear, anti-weld, and demulsibility properties. This improved hydraulic oil contains (1) petroleum hydrocarbon oil; (2) esters of dibasic and monobasic acids; (3) butylated phenol; (4) phenol; (5) sulfurized fatty oil; (6) fatty acid; and (7) sulfur scavenger. This hydraulic oil has a reduced tendency towards sludge formation and has, therefore, an increased lifetime. (mineral oils was used)
Reference may be made to U.S. Pat. No. 6,300,292 Konishi, et al. Oct. 9, 2001 Nippon Mitsubishi Oil Corporation (Tokyo, JP) Hydraulic oil composition. A hydraulic oil composition which is excellent in oxidative stability, lubricating properties and biodegradability; comprising vegetable oil as base oil, and one phenol antioxidant, an amine antioxidant and a zinc dithiophosphate antioxidant. (edible vegetable oils are used)
Reference may be made to U.S. Pat. No. 6,436,883, Nieh, Aug. 20, 2002, Huntsman Petrochemical Corporation (Austin, Tex.) Hydraulic and gear lubricants. Provided herein are functional fluid compositions useful in hydraulic fluid and gear oil formulations. The formulations according to the invention include a predominant amount of at least one polyoxyalkylene glycol derived from the addition polymerization of an alcohol in the presence of an alkylene oxide mixture, which contains a substantial amount of ethylene oxide. Fluids according to the invention exhibit suitable lubricity and stability characteristics and are generally water soluble to a degree sufficient to preclude formation of a sheen on the surface of a body of water into which a fluid according to the invention is brought into contact. (polyethylene glycol was used)
Reference may be made to U.S. Pat. No. 5,366,658, Hoppe, et al., Nov. 22, 1994, Huls Aktiengesellschaft (Marl, Del.) Use of polymethylalkanes as biodegradable base oils in lubricants and functional fluids The invention relates to the use of polymethylalkanes having terminal methyl groups and methylene and ethylidene groups in which the total number of C atoms n+2 m+2 is 20 to 100 and the ratio of the methyl and methylene groups to the ethylidene groups is 3 to 20:1 and the ethylidene groups are always separated by at least one methylene group, as biodegradable base oils for lubricants and functional fluids. Suitable polymethylalkanes are obtained by oligomerization of .alpha.,.omega.-diolefins, for example in particular according to P 41 19 332.6, or by pyrolysis of ethene/propane copolymers and subsequent hydrogenation in each case. The polymethylalkanes can be combined with conventional additives and other degradable or non-degradable base oils. (polymethyl alkanes was used)
Reference may be made to U.S. Pat. No. 4,783,274 (Jokinen et al., Nov. 8, 1988) Concerned with an anhydrous oily lubricant, which; is based on vegetable oils, which is substituted for mineral lubricant oils, and which, as its main component, contains triglycerides that are esters of saturated and/or unsaturated straight-chained C.sub.10 to C.sub.22 fatty acids and glycerol. The lubricant is characterized in that it contains at least 70 percent by weight of a triglyceride whose iodine number is at least 50 and no more than 125 and whose viscosity index is at least 190. As its basic component, instead of or along with the said triglyceride, the lubricant oil may also contain a polymer prepared by hot-polymerization out of the said triglyceride or out of a corresponding triglyceride. As additives, the lubricant oil may contain solvents, fatty acid derivatives, in particular their metal salts, organic or inorganic, natural or synthetic polymers, and customary additives for lubricants. (edible vegetable oils are used)
Reference may be made to U.S. Pat. No. 5,538,654 (Lawate et al., Jul. 23, 1996) Describes a food grade lubricant composition, which is useful as hydraulic oil, gear oil, and compressor, oil for equipment in the food service industry. This composition comprises (A) a major amount of a genetically modified vegetable oil and (B) a minor amount of a performance additive. In other embodiments the composition contains either (C) a phosphorus compound or (D) a non-genetically modified vegetable oil. (edible vegetable oils are used)
Reference may be made to U.S. Pat. No. 5,580,482 (Chassan et al., Dec. 3, 1996) A lubricant composition stabilized against the deleterious effects of heat and oxygen said composition comprising a triglyceride oil or an oil which is an ester wherein unsaturation is present in either the alcohol moiety or the acid moiety and an effective stabilizing amount of either an N,N-disubstituted aminomethyl-1,2,4-triazole or an N,N-disubstituted aminomethylbenzotriazole and a higher alkyl substituted amide of dodecylene succinic acid. (edible vegetable oil with an additive was used)
Reference may be made to U.S. Pat. No. 5,888,947 (Lambert et al., Mar. 30, 1999) A composition that has three main components: a base oil, an oil source containing hydroxy fatty acids and an oil source containing vegetable or animal waxes. The base oil used in the reference needs to consist of primarily triglycerols (triglycerides) and mono- and diglycerols (glycerides) and free fatty acids. The composition further consists of vegetable oils where the glycerols contain hydroxy fatty acids, preferably making up 5% to 20% of the oil. A third major component is waxes composing 5% to 10% of the oil additives by volume. Additional synthetic mimics or natural products derived from animal or vegetable compounds may be added up to 5% of the compositional volume. (glycol fatty esters and fats are used)
A patent filled by the inventors of the present invention disclosed the use of Heavy Alkyl Benzene alkaline earth metal sulfonates that are used as detergent-dispersant-anti rust additive in various types of lubricants (Patent application IPA number 1306/DEL1998 & 1307/DEL/1998 by A. K. Singh et al assigned to CSIR). The alkyl benzenes are mono, di and poly substituted alkyl aromatics having one benzene or toluene aromatic ring and straight or branched paraffinic chains having carbon atoms 1 to 15 preferably 10 to 15, preferably mono and di alkyl benzene. Alkyl benzenes are produced as by-products during the preparation of, (1) linear alkyl benzene (LAB) in detergent industry, (2) heavy aromatic produced in catalytic reformer, and (3) naphtha or gas steam cracker liquid product. Alkyl benzene consists of substituted benzenes and no poly-aromatics/condensed ring or olefinic compounds are present in the alkyl benzenes. It can be used as an alternate to mineral base stock of lubricants. It will reduce the hazard potential of the lubricants. It will provide required properties such as good hydraulic properties, lubricity, load carrying, stability, anti-corrosion properties and more eco-friendliness.
There is a need for developing new hydraulic fluid composition, which is free from harmful, polynuclear aromatic hydrocarbons generally found in mineral oil and produce less pollution. These objectives must be met, while simultaneously satisfying stringent performance standards, e.g., good lubricity, load carrying, stability and anti-corrosion.